CODEWITHSUNDEEP
r
user86533
user86533

Reputation: 333

R: Add values to vector with a loop

I´m new to R and I´d like to execute the following simple code:

vec_color <- c("red", "blue", "green", "yellow", "orange")
col_vec_final = c()

i <- 1
while (i <= 3)
{
col_vec_final <- c(col_vec_final, i = vec_color[i])
i <- i+1
}

I´d expect to get the following output:

col_vec_final
     1      2     3
 "red" "blue" "green"

However I only get the following:

col_vec_final
     i      i     i
 "red" "blue" "green"

Could you please help me with that and tell me whats wrong with my code?

Thank´s in advance!

Upvotes: 1

Views: 2712

Answers (1)

Rich Scriven
Rich Scriven

Reputation: 99391

vec_color <- c("red", "blue", "green", "yellow", "orange")

Firstly, keep in mind that you can vectorize this entire operation and do it all in one line, like this -

l <- seq_len(3)
( col_vec_final <- setNames(vec_color[l], l) )
#      1       2       3 
#  "red"  "blue" "green"

As far as your while() loop goes, I'd recommend you allocate the result vector first, as it's better practice and a lot more efficient than building a vector in a loop - 

n <- 3
col_vec_final <- vector(class(vec_color), n)

then do the following - 

i <- 1
while (i <= n)
{
    col_vec_final[i] <- vec_color[i]
    names(col_vec_final)[i] <- i
    i <- i + 1
}

col_vec_final
#      1       2       3 
#  "red"  "blue" "green"

Upvotes: 1

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